A striking box of this kind is known from Dutch Pat. No. 152,626 or British Pat. No. 1,515,531 for night lock bolts on doors in prisons.
Previously such a mechanism comprised a toggle-joint lever and the signalling switch is operated by the bolt stop.
This made it possible, when the bolt stop is retracted, to insert a piece of cardboard or a similar object in the striking box with the result that, in the position blocked by the toggle-switch lever, the latter cannot fully reach the rest position, and the bolt stop is so close to its end position that the signalling switch is operated. The striking box then appears to be closed, but the bolt stop can be pushed back. Besides this indicated abuse, accumulated dirt can also cause this malfunction.